RRC ID 49710
Author Liu YC, Hale ME.
Title Local Spinal Cord Circuits and Bilateral Mauthner Cell Activity Function Together to Drive Alternative Startle Behaviors.
Journal Curr Biol
Abstract The reticulospinal Mauthner cells (M-cells) of the startle circuit have been considered to be dedicated to one basic motor output and the C-type startle response in fish. The neural circuit underlying the C-start, a startle behavior in which the fish forms a "C"-shaped body bend has been described in depth in goldfish and zebrafish [1, 2] and is thought to occur in other species [3, 4]. However, previous research has shown that some species can perform a second type of startle called the S-start [5-7]. This startle response, in which the first movement creates an "S"-shaped body bend achieved with regional muscle activity on left and right sides, cannot be explained by M-cell circuit models. Here we use larval zebrafish to examine the S-start circuit. Since S-starts are elicited through tail stimulation [5-7] and ablating M-cells abolishes short-latency tail-elicited startles [8, 9], we hypothesized that M-cell activity was necessary for S-start generation. Our findings show that the M-cells fire simultaneously to generate the S-start. However, simultaneous M-cell spikes generated through direct current injection were not sufficient to generate S-starts. Through recordings of motoneurons, inhibitory interneurons, and sensory neurons, we uncover a mechanism for generating alternative startle behaviors; local sensory inputs drive inhibitory interneuron activity, which inhibits caudal motoneurons and pre-conditions their excitability prior to the arrival of M-cell spikes in the tail. We suggest that this motoneuron hyperpolarization can bias motor output to left or right sides, determining whether the fish performs a C-start or an S-start behavior.
Volume 27(5)
Pages 697-704
Published 2017-3-6
DOI 10.1016/j.cub.2017.01.019
PII S0960-9822(17)30019-2
PMID 28216316
MeSH Animals Interneurons / physiology* Motor Neurons / physiology* Neural Pathways / physiology Reflex, Startle / physiology* Sensory Receptor Cells / physiology* Spinal Cord / physiology* Zebrafish / physiology*
IF 9.601
Times Cited 10
Zebrafish Tol-056